Auto merge of #76558 - tmandry:rollup-bskim2r, r=tmandry

Rollup of 7 pull requests

Successful merges:

 - #74787 (Move `rustllvm` into `compiler/rustc_llvm`)
 - #76458 (Add drain_filter method to HashMap and HashSet)
 - #76472 (rustbuild: don't set PYTHON_EXECUTABLE and WITH_POLLY cmake vars since they are no longer supported by llvm)
 - #76497 (Use intra-doc links in `core::ptr`)
 - #76500 (Add -Zgraphviz_dark_mode and monospace font fix)
 - #76543 (Document btree's unwrap_unchecked)
 - #76556 (Revert #76285)

Failed merges:

r? `@ghost`